Sam Kelly commenced her time at Waterloo Road at the age of fourteen. She is the third of five children born to troubled Rose Kelly. Her half-brothers Marley, Earl and Denzil were also pupils at Waterloo Road. She also has a baby brother, Prince, who is not featured very much during the series. She grew up around the country after her troubled mother uprooted the family, which she started in east London, on several occasions. The family's wayward nature was attributed to the abusive and manipulative actions of Sambuca's father, Reynold. Viewers soon learn that although Sam might come across as abrasive, she is a highly compassionate individual.
Named after her mum’s favourite drink, Sambuca is essentially a good kid who often finds herself drawn into trouble by the tough Waterloo Road environment. Over the course of the time that Sam spends at Waterloo Road, she often finds herself in trouble as a consequence of her endeavours to provide assistance to her friends. Sam proves herself to be an exceptionally loyal individual with a gigantic heart, as is proven when she provides assistance to one of her classmates, Harry. Sam is used to fighting her own corner and as a result springs to the defensive a little too readily.
On Sam's first day at Waterloo Road, she is portrayed as hostile, disruptive and angry at the world. Although she managed to disrupt Matt Wilding's music class by complaining about the music, she showed remorse when she was forced to face the wall for the remainder of the lesson as punishment. Matt later sympathised with her.
Aftermath of Denzil's arrest, Sam tried to influence and inspire Rose to start going into education by attending Waterloo Road's adult educational class. Although Rose attended the classes, unbeknownst to Sam, Rose became uncontrollably drunk and got into physical altercation with fellow classmate, Candice. when Sam discovered what occurred, she became cross with her mother and made it clear that she was unhappy with how her mother had acted over the years.
Sam's life become complicated once again when she was temporarily fostered by Matt when her violent father Reynold returned. Although Sam categorically denied that her father was ever violent towards her, it was felt that Sam's safety necessitated her being fostered. Sam wasn't too keen to stay with him and soon made Matt the target of a practical joke. For example, she steals a packet of 'Wind-Eze' from his medication cupboard and makes it known to the entire school. Sam and Matt, however, soon become close and Sam views him a father-figure in her chaotic life. Reynold soon becomes uncontrollably jealous of Matt's secure relationship with Sam. Rose then decided to shop him to the police because he had stolen Matt's LCD television. When Sam is told she can return to living with her mother she doesn't seem that happy. Matt encouraged Sam to return to where Sam is able to be happy. Matt also made it known to Rose that he will be there if she ever needs assistance.
However, their celebration was short-lived when Earl fatally shoots his girlfriend Maxine Barlow in a jealous rage. He was swiftly cornered by the police and duly arrested. It transpired that Earl killed Maxine after she dumped him over allegations that he was the father of a newborn baby boy whose mother had turned up at the school that day. When Maxine confronted the girl, she alleged that Earl was the father who did not wish to have a role in the baby's life.
In 4x13 Sam became close to Kyle, a Traveller who, along with his family, set up base on the school grounds. The two became good friends, even sparking a relationship from Kyle's short time at Waterloo Road. Sam stuck up for him and his family when he was the victim of bullying from teacher Grantly Budgen and pupils Bolton and Paul. During a football match organized by Eddie Kyle's feelings for Sam became evident when they shared a kiss. At the end of the school day as Kyle and his family made plans to become regulars at the school, the council arrived to violently move them on. Knowing this would be their final meeting, Kyle gave Sam his ring as a token of his friendship. Saddened, Sam stood and watched as the Travellers — and Kyle — left Waterloo Road for good.
In Series 5, Sambuca and Lauren Andrews' fiery spirit is inflamed by the arrival of Amy Porter and Siobhan Mailey, the two of them hurling insults at one another. Each of them performed a duet dance routine at a talent show, dancing to "Lady Marmalade". When they got on stage, Amy and Siobhan threw buckets of slime at the girls, but they still did their act. In episode 15, Sam hid a pair of shorts in Bolton Smilie's bag and was caught. But Sam whispered "Run" and went after him. After making a break for it, Sam took Bolton to her favourite place and started throwing rocks at an old wrecked boat. A few minutes later, Sam and Bolton shared a romantic kiss. After Bolton started to ignore her, enraged Sam started hurling insults to him when they were playing a basketball game in episode 16. She then threw a glass full of smoothie over him. When Bolton was still ignoring her, she asked Paul Langley to the prom to get him jealous. This worked and Bolton took her instead. They were crowned Prom King and Queen.
When Sam returned to school after the summer holidays, she was received coldly by Lauren because she felt that Sam spent too much time with new boyfriend Bolton. Lauren and her new sidekick Amy decided to ignore Sam, who felt hurt by their actions. Sam attempted to help new student Ruth Kirby, who had been home schooled by her father and had problems fitting into Waterloo Road. Sam endeavoured to be nice to Ruth, only to be treated rudely. Ruth behaved poorly towards Sam, which resulted in Sam punching her in the nose. Much to Sam's displeasure, she is then excluded for two weeks by new head Karen Fisher.
When Tom Clarkson supported Sam, she returned to Waterloo Road. During the series, it is obvious that Sam is motivated by a strong desire to help other people. For example, she wanted to help Harry, who was troubled by his suspicions that his father was having an affair. Sam agreed to help Harry, even though it could cause trouble for her.
Later in the series, Lauren’s resentment is taken a step too far when she allowed Sambuca to take the blame for bringing in drugs that were actually belonged to Amy. What Sam was actually trying to do was buy the drugs off Amy and hand them over to her Spanish teacher Francesca Montoya. Amy, however didn't trust Sam and gave her oregano pretending it was the drugs and she and Lauren followed Sam to Miss Montoya's classroom where they see her handing the "drugs" over. Angered by this, Amy and Lauren conclude that Sam had told on them to Miss Montoya, even though she hadn't. Amy persuaded Lauren to plant the actual drugs on Sam which resulted in her nearly getting excluded. Disgusted with both of them, Sam decided to leave Waterloo Road for good, despite Deputy Head Christopher Mead trying to reason with her. However when confronted by Miss Montoya Lauren told the truth afterwards and admitted the drugs were Amy's. Karen Fisher was disgusted that Lauren and Amy had attempted to blame Sambuca and punished them both by making them write an apology letter to Sam and her mother, Rose Kelly. Lauren ran after Sam as she was leaving and told her she was sorry and she had told the truth in the end. Lauren also tries to make friends with her again but Sam tells her she can't see how they can be friends anymore because she is leaving Waterloo Road. Lauren is saddened by this, knowing it was mainly her fault that she has lost her best friend.
Sam returned in episode 15 in which she appears to have forgiven Lauren but not Amy. She returned simply to make sure Denzil doesn't get into trouble but her and Finn soon start arguing. Harry Fisher shows Sam emails he has been sending to staff on his mother's phone but when Karen works it out Sam plants the phone in Amy's bag at an attempt at payback. Harry then goes to his mother saying he sent the texts and covers for Sam by saying he planted the phone. Afterwards Sam admits to Amy she planted it but it didn't make her feel better and they make friends. Finn then reveals he is Denzil's new mentor much to Sam's dismay.
Sam continues to be a harsh critic of Finn and remains suspicious of his motives. In spite of the fact that it seems as if Finn's intentions are sincere towards Denzil, Sam behaves harshly towards Finn. For example, Finn endeavours to prevent Denzil from viewing pornography on Wayne's telephone. Sam thinks that Finn is encouraging Denzil to view the images on Wayne's phone. When Sam realises that Finn was only trying to help, she apologises to Finn, who accepts Sam's apology. The two share a kiss. In episode 20 when Finn gets Kyle Stack (George Sampson) kicked off the cast for the pantomime, and he replaces him himself, Sam is disgusted with him, as she saw that the pantomime had actually meant a lot to Kyle even though he pretended that he couldn't care less about it, and as Finn keeps trying to apologize, Sam ignores him. But, when Denzil does a dangerous stunt walking across the top of a railway, Finn goes up to save him, Denzil gets away, but when Finn realises he can't get over he falls and lands on his back, he is rushed to hospital, where Kyle says he is sorry and they unite and so do him and Sam.
In the first episode of Series 7, Sambuca and many other students at Waterloo Road, believe that Kyle Stack is the father of his girlfriend's baby. When Sam asks him what he is going to do about it, she reminds him that both her dad and Kyle's were not proper father-figures as both were not a consistent present in the lives of either child. This encourages him to go and find his girlfriend Ali. Sam is very approving of this decision, and when Lauren, Amy and Finn make jokes about him being a father behind his back, she defends him, saying that for once, he'd gone to do the right thing. Later in the day, Sambuca collapses on the grass outside her home. A shocked Tom calls for her mother Rose as Sambuca violently fits on the ground.
The cause of her headaches is later diagnosed as brain cancer. . In spite of her diagnosis, Sam attends school and tells everybody that her severe headaches are attributed to migraines. Her fragile emotional state allows her to be the only Waterloo Road student who makes an effort to speak kindly to Martin, a recent arrival at the school who reveals the fact that he has transgender issues and that he hates himself. In episode three, it was revealed that Sambuca's cancer was incureable. Tom Clarkson frantically searched the internet for possible treatments outside the National Health Service but Rose insists there's nothing they can do, and they have to find a way to tell her. It was too late, however, as Sambuca had already visited her doctor to ask about the types of medication she'd received and what they do, and was stunned by the shock news that she's dying.
In episode four, Sambuca was surprised by a special meal from Rose, Tom, Finn, Amy, Lauren and the rest of the school. Finn later breaks up with Sambuca after finding it very difficult to cope with the pressure that has been put on him after finding out of Sam's terminal illness. He realises the errors of his ways later, however, and turns up at her house to apologize. They make up and he tells her he'll be with her until the end.
Sam was persent at the opening of the school cafe and wrote in the wall, "Sam Kelly woz 'ere 2011".
Finn and Lauren took her to Blackpool to go find her father, with no success. She felt free after they ran from a restaurant after Finn could not pay for the bill. She assured Lauren that she wouldn't mind if she wanted to get with Finn, but Lauren denied any feeling's for Finn.
She died in her sleep, with Tom and Rose at her side.